My Wilsons weigh in at over 400 lbs. a side. I replaced the factory supplied casters, which had started to break down, with heavy duty commercial parts and opted to leave them on rather than spike them (lifting the speakers to install spikes is fraught with hazard and the likelihood that you will slightly change the alignment and be unable to correct that easily). Wood floors.
OTOH, my big Vandersteens do sound better with spikes, so YMMV.
OTOH, my big Vandersteens do sound better with spikes, so YMMV.